Friction device for operating knobs in adjustable apparatus



R. 4 J H J w R M 7 E 0 MG T 6, TW r .2 MS VM WHY. AB GS MN l H NU HM mmmm ,EP9 Rwml ERE GOL NF mamme. LIUMv mmm .DAM ANNU .OIF HHS CB 1m mK Dec. 1, 1953 Patented Dec. 1, 1953 FRICTION DEVICE FOR OPERATING KNOBS IN ADJUSTABLE APPARATUS Harry A. Hilsinger, Jr., East Orange, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a, corporation of New York Application December 22, 1951, serial No. 262,986

4 Claims.

This invention relates to control knobs and more particularly to a control knob having a self-contained adjustable brake mechanism, and particularly suitable for use on apparatus adjustable by means of a rotatable shaft.

An object of this invention is the provision of a, control knob wherein the knob may be so adM justed that the shaft secured thereto may be frictionally loaded to provide a braking force from a deadlocked condition, through varying degrees of friction to a freely rotatable condition.

The control knob of this invention comprises a housing or main body member having a longiw tudinally extending bore therein which communicates with recesses in the inner and outer ends thereof and has positioned therein a suitable apparatus shaft. The free or inner end of the shaft is arranged to be connected to the apparatus to be adjusted and the outer end is secured in the knob housing, and is journaled in a flanged sleeve or bushing which is secured against rotation to a suitable panel. The flanged portion of the sleeve is in frictional engagement with an adjacent washer which is arranged to be forced against the flange of the sleeve when the longitudinally extending pins, slidably mounted in knob housing, are forced against a second washer positioned in Contact with the first washer, by means of a dished member located in the outer recess of the knob housn ing which exerts a varying force on the pins when means, also located in the outer recess of the knob, is adjusted. This structure permits the apparatus shaft, secured to the knob, to e be adjusted from a freely rotatable condition to a deadlocked condition to provide a braking action on the shaft which will cover a wide range of loading.

The invention and the features thereof will be clearly understood from the following detailed description when read in connection with the accompanying drawing in Which:

Fig. l is an exploded view in perspective of a knob assembly constructed in accordance with this invention;

Fig. 2 is a side elevational view partly in section and illustrates the knob connected to the shaft of a potentiometer; and

Fig. 3 is a side elevational view and illustrates the knob used in cooperation with a potentiometer and switch mechanism wherein longitudinal movement of the knob and its associated shaft operates the switch and rotatable movement operates the potentiometer.

Referring now to the drawing, the knob of this invention may be constructed from any suitable material, for example metal, and comprises a main body or housing portion I0 having recesses II and I2 at its inner and outer ends. Communicating with the recesses II and I2, and extending longitudinally with respect to the knob housing IE) is a central bore I3, which has se' cured therein, as by a press fit, the bushing I4. The bushing I4 is provided with a longitudinally extending bore I5 having a shoulder portion I6 adjacent its outer end. Projecting from the outer end of the bushing I4, above the surface of the recess I2, is the internally threaded protuberance IG. Located in the longitudinally ex,- tending bores II, which communicate with the recesses II and I2, are the pins I8 which are spaced equidistant, are slidably mounted thereand have their end portions projecting into the recesses II and I2.

Located in the wall of the knob housing I 0 and extending at right angles with respect to the bore I5 is the threaded aperture 2U for receiving the set screw 2|.

Positioned over the protuberance I6 in the outer recess I2 is the apertured concavo-convex isc 2I having a notch 22 on its periphery which is arranged to register With the boss 23 on the inner wall of the recess I2 to prevent displacement of the disc. Bearing against the convex or outer surface of the disc 2|, and held in position thereagainst, in adjusted relation by means of the screw 24, is the shouldered cap member 25 which is also notched on its periphery, to prevent movement. Located in the rear recess Il, adjacent the end of the bushing I4 and bearing against the ends of the pins I8, is the washer member 26 which is prevented from rotating by the indentations I9 which register with the ends of the pins I8.

Located at the end of the bushing I4, and in frictional engagement with the indented washer 26 is the friction or brake washer 21. This washer is confined between the flanged surface 28 of the hub or sleeve 29 and the Washer 26, and is held in position by the washer 30 located on the body portion of the hub 29 and which bears against the inner surface of the flange 28. The washers 26 and 21, the hub 29 and the washer 30 are all held in juxtaposition by means of the spring locking ring 3I which bears against the washer 30 and is positioned in the groove 32 in the recess I l.

In order to prevent rotatable movement of the hub 29, the inner end thereof is provided with projecting ears 33 and 34 which are arranged to register with the slots 35 and 36 in the panel 31, which communicate with the shaft aperture 38. The shaft 39, which may be connected to any suitable apparatus, for example the potentiometer 4l), is provided with flats at its end portion to provide a bearing "surface for the set screw 2l to secure the vknob to the shaft 39.

In Fig. 2 there is illustrated the knob of this invention operatively connected to the shaft "of a potentiometer 40 which is securedto the ipanl 31 by means of the bracket BR. n.In this figure the hub member 29 is shown as .being 'securely held against rotation by means `o'f Athe years 33 and 34 registering with the notches 35 and 36 in the panel thereby providing the stationary element of the braking mechanism. vvThe hub T29. which forms the stationary braking element of the brake mechanism, is confined between the Irotatable braking elements which comprise .the washers 21 and 3U'bym'eans-of the lo'cfkingring 3l Jon the inner end Vand the concavo-convex disc `2'I, the cap I25 'together with the set screw 24 'on the outer end. The 'pins I8 are forced against Athe washer 25, which in turn is vforced against the vwasher 21 and into frictional engagement with the flange `on the hub member 29, by pressure of the concave-convex `disc 2`I on thepins '(8 by means of the cap 25 anda screw I2'4. By adjusting the .screw 24 the pressure on the concave-convex disc 29 may be varied 'thereby varying the pressure .on the pins f8 and -consequently varying 'the friction between `the washers 2b and v21, the Ahiib 28 and the washer 30. Thus, when the screw 24 is turned home, in a clockwise direction, `the shaft 39 will be in .a deadlocked position and when turned counter-clockwise, `to release the .pressure on the concave-convex discl2i, theshaft will be freely rotatable, thereby `providing a means 'for adjustably braking the rotary motion of the shaft 39 `and the adjustable elementsa'ssociated therewith.

The knob of this Ainvention maybe so connect'ed to the operating shaft of an instrument thatlbothrotary andlongitudinal movementmay be 'imparted thereto. As shown -in "Fig. "3, a shaft member 4l, having a tapered collar 42 thereon issecured in the knob housing by means f of ythe set screw `2l in lthe same manner as 'the shaft "39 as heretofore described. 'The opposite end of the shaft N4l is slotted a't VVHandi-has slidably positioned therein the flattened portion 44 of the shaft A15 which is operatively connected to the `potentiometer '40. 'Thus lthelknob maybe moved longitudinally as shown by the dot and dashlines, andsince the ears 33 and '3:4 have 'a length greater than the thickness of Ithe panel they will ride 2in the .slots 35 and 36 as the knob assembly and the `shaft 4| is moved inwardly and outwardly.

bp'eratively associated Withtheltapered-'shoulder 142 on the 'shaft 4l, is the operating arm 45 o'faswitchmechanism '41, which when the knob assembly is in its extended position, as Vshown by ltlie full lines, the .switch 'will be in its unoperatedlposition since the "arm "46 isfully extended and vout of contact with the collar 42. However, whenthe `knob assembly is move'dinwardly as shown by the dot and dash lines, Lthe collar'42 willengage the arm :46, move it inwardly and operate the switch and at the same time the knob assembly may be rotated'to adjust the potentiometer 40.

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Iii)

Although I have shown and described herein the preferred embodiment of my invention, it is to be understood that various changes and modifications may be made therein without departing from the scope and spirit of the invention.

What is claimed is:

l. A control knob comprising Ain combination .a-.panel, a body member having a central bore Itherein, said body member having inner and l'outer-end recesseezarhub member having a central lbore therein, said hub member having a flanged endportion journaled in the inner re- 'cess of said body memben a shaft rotatably mountedlinsaid .hub member extending through said panel and .secured to said body member. means on said hub member in engagement with 'said 1panel for preventing the rotation of said hubmember, brake means in the inner recess of said'bo'dy member in frictional engagement with the iianged end of said hub member, for braking the rotation of said `knob `'and -said shaft, and means in theouter 'recess of said'body member operatively connected to "said brake means, 'for varying the 'friction "thereof,

2. A control -knob *for nrotatable shafts "comprising a hollow body member having inner and outer en'd recesses, Aa 'hub member vhaving a central :bore therein, said hub member "having fa hanged end "portion journaled 44in the inner recess of said body tfor `supporting :said knob, a shaft rotatably mounted in said `hub member and secured to said body member. braking means in said inner 'recess vof said body member in engagement with the flanged `rnd of said hub member 'for braklngthe "rotation of Vsaidlmb, and means in the outer recess 'df said Ebo'dy member operatively connected to said "braking means for .regulating the friction thereof.

'3. A control :knob for .rotatable shafts `com-- prising a 'hollowbody member Vhaving inner "and outer end recesses, a Lhub member `having a central boretherein, 'sai'd hub member 'having a flanged en'd .portion vjournaled in the inner recess of said .body member for supporting said knob, a shaft rotatably "mounted in said 'hb member and secured^tosaid"body memberfbra-k ing meansln said innerrecess "of saidibody mem# ber in engagement Awith "the flanged f end of `said hub member for 4braking `the rotation of `saliti knb,;and lmeans'in the outer recess of said body member `operatively connected Ito 'said braking means, and comprising Vam `-adjustingscrew meme ber and members operatively linterposed 4between saidiadjustln'g member'and said braking means for 'transforming `displacement of said adjusting memberinto pressure on'said braking means, lfor reglatingthe Jfriction thereof.

'4. A control "'knb -comprising `in combination apanel, a body member having a central "bore therein, said body member 'having 4inner 4and outer v.end recesses. 'a hub member having 'a central bore "therein, vsaid hub member having a flanged end. portion journaled inthe Linner Vrecess r of .said body member, a shaft rtatablymounted in said hub member extending through said `panel andsecured to said body member, means on fsai'd lhub member in engagement with y-sa'id panel "for preventing vthe rotation of said hub member, Abrake means in the v'inner recess Aof said body member in "friction'al engagement 'with `the flanged end 'of 'said "hub member, 'for braking the rotation of said knob 'and said shaft, and means in the Souter recess -of said body rmember operatively connected to said "brake means 'and References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Clickner Apr. 10, 1945 Aitcheson July 6, 1948 Haury May 23, 1950 Jeffrey May 30, 1950 Waldron July 10, 1951 

